1. Field of the Invention
This invention relates to a communication field, and more particularly to a method, apparatus, mobile communication terminal, computer program and storage medium for adjusting frequency error of a terminal.
2. Description of the Prior Art
Dual-SIM-Dual-Call (DSDC) is a new feature of current mobile communication terminals, which enables end users to use two different network operator's services with two SIM (Subscriber Identity Module) cards. A mobile communication terminal with DSDC feature can support two SIM cards from different operators and keep camping on the network and standby. Moreover, differing from the Dual-SIM-Dual-Standby (DSDS) technology, DSDC is able to originate or receive services from the two camped networks simultaneously. That is to say, one SIM card in a call will not impact on another SIM card browsing Internet or answering another call.
Due to the fact that different operators often use different 3G (3rd-Generation) radio access technologies, it is impossible for a single SIM card to support a mobile communication terminal to use another operator's service if the end user does not change the mobile communication terminal number. So this market demand makes that the mobile communication terminal with DSDC feature is strongly recommended by some operators and also very popular among end users.
So far there are two main structures for the mobile communication terminal with DSDC feature:
One is that there are two modem systems with different clock sources in the mobile communication terminal. Such a structure is very easy to be realized, but also in high cost.
Another one is that there are two modem systems in the mobile communication terminal, but these two modem systems use a same clock source (referring to FIG. 1), which is in low cost. These two modem systems may correct frequency error by correcting their PLL (Phase Locked Loop), but it needs a long response time. Sometimes such long response time may affea the performance of the mobile communication terminal seriously and even lead to call failure.
Thus, a method for quickly correcting the frequency error of the mobile communication terminal is desired.